Wikipedia
Pornography
Pornography or porn is the depiction of explicit sexual subject matter for the purposes of sexual excitement.
Over the past few decades, an immense industry for the production and consumption of pornography has grown, with the increasing use of the VCR, the DVD, and the Internet, as well as the emergence of social attitudes more tolerant of sexual portrayals. Performers in pornography are referred to as pornographic actors (or actresses), or the more commonly known title "porn star" and are generally seen as qualitatively different from their mainstream counterparts. Amateur pornography has become widely popular and generally distributed via the Internet for free.
Pornography may use any of a variety of media, ranging from printed literature, photos, sculpture, drawing, painting, animation, sound recording, film, video, or video game. However, when sexual acts are performed for a live audience, by definition it is not pornography, as the term applies to the depiction of the act, rather than the act itself. Thus, portrayals such as sex shows and striptease are not classified as pornography.
From country to country pornography is considered and treated differently, both culturally and legally, whether depictions of nudity in art or photography.
Etymology
The word derives from the Greek πορνογραφία (pornographia), which derives from the Greek words πόρνη (pornē, "prostitute" and pornea, "prostitution"), and γράφω (graphō, "I write or record," derived meaning "illustration," cf. "graph"), and the suffix -ία (-ia, meaning "state of," "property of," or "place of"), thus meaning "a written description or illustration of prostitutes or prostitution."
History
The depiction of sexual acts is as old as civilization (and can be found painted on various ancient buildings), but the concept of pornography as understood today did not exist until the Victorian era. Previous to that time, though some sex acts were regulated or stipulate read more at » http://en.wikipedia.org/wiki/Pornography